다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Elements Of X Ray Diffraction

A precipitation-hardened high-entropy alloy with outstanding tensile properties

Self-catalytic growth of horizontal and straight Si nanowires on Si substrates using a sputter deposition technique

Understanding of the origin of some of the intermediate frequency modes (IFMs) in the Raman spectrum of carbon nanotubes has remained controversial in the literature. In this work, through controlled introduction and elimination of defects in carbon nanotubes, we attempt to isolate the IFMs due to structural defects from that of the combination modes in single walled carbon nanotubes (SWCNTs). Our investigations on pristine and defect engineered SWCNTs using ion-irradiation, thermal annealing, and laser processing show systematic changes in the IFMs in the range 400–1200 cm−1 and its manipulation with the processing parameters. In particular, we found that the intensity of IFM at 929 cm−1 scale up with the increasing defect concentration, while that at 668 cm−1 follows opposite behavior. New IFM peaks were observed upon the creation of a controlled amount of structural defects through 30 keV N+ ion irradiation. Elimination of defects through vacuum annealing results into reduction of intensity of some IFMs identified as defect related, while the intensity of characteristic combination modes correspondingly increases. Our results show that the IFMs observed at 709, 805, 868, 926, and 1189 cm−1 are due to structural defects in the SWCNTs, while those in the range 400–550 cm−1 and at 669 cm−1 are due to the combination modes. Our x-ray photoelectron spectroscopy analysis on ion irradiated SWCNTs supports the Raman results.

Distinguishing defect induced intermediate frequency modes from combination modes in the Raman spectrum of single walled carbon nanotubes

An isothermal spectroscopic technique called time‐analyzed transient spectroscopy (TATS) has been used to study photoinduced current transients in undoped semi‐insulating GaAs. It is demonstrated that this has many advantages over conventionally used photoinduced transient spectroscopy (PITS). Specifically, TATS provides both quantitative measure and qualitative insights to the nonexponentiality of current transients commonly encountered in these materials. Using this spectroscopy, features related to enigmatic negative peaks resulting from rising current transients in these materials are reported. A simple kinetic model has been proposed to explain the essential features of rising transients leading to negative peaks in both TATS and PITS spectra.

Nonexponentiality in photoinduced current transients in undoped semi‐insulating gallium arsenide

Low-energy (keV) Si ions are implanted on mask-pattered Si wafer at doses above amorphization threshold for a variety of implantation conditions (ion dose, energy, temperature) and post-implantation annealing. Precise measurement of the surface swelling (step-height) on the amorphous Si layer was carried out using an atomic force microscope (AFM). Thickness and microstructure of the ion-damaged layer was evaluated by transmission electron microscopy (TEM) measurements. The measured step-height in excess to that contributed by implanted ions shows a cube root dependence on the Si ion dose. The swelling heights studied for two different energies of Si ions show identical step-heights. Implantation at low temperature (77 K) shows a reduced step-height, indicating possible contribution of migrated Si atoms in the swelling. We propose that excess swelling is caused by migration and segregation of the displaced Si atoms from the bulk to the surface leaving behind corresponding vacancies in the lattice. Ellipsometric studies of the similarly damaged layer profile provide supporting evidence for surface segregation of Si atoms over the amorphous layer.

Studies on the surface swelling of ion-irradiated silicon: Role of defects

Growth kinetics of hybrid perovskite thin films on different substrates at elevated temperature and its direct correlation with the microstructure and optical properties

P. K. Giri

Papers

Self-catalytic growth of horizontal and straight Si nanowires on Si substrates using a sputter deposition technique

Distinguishing defect induced intermediate frequency modes from combination modes in the Raman spectrum of single walled carbon nanotubes

Nonexponentiality in photoinduced current transients in undoped semi‐insulating gallium arsenide

Studies on the surface swelling of ion-irradiated silicon: Role of defects

Growth kinetics of hybrid perovskite thin films on different substrates at elevated temperature and its direct correlation with the microstructure and optical properties